What is TXV

[ramlam]

I think the Comfort-R feature on my Trane furnance requires an a/c coil with TXV. Does anyone know what TXV is and why it would be critical for use with Comfort-R? I have an 11 seer, 6 year old Lennox a-coil and don't know if it has TXV.

[coolguysfl]

Thermal eXpansion Valve

The TXV modulates to allow the precise amount refrigerant to flow thru the evap coil to maintain ideal coil temp. It modulates from the heat or lack of heat sensed by the sensing bulb on the suction line leaving the evap.

The TXV is sized to the coil & condenser and usually mandates the requirement of a hard start kit to assist the compressor in starting.

[smokin68]

A txv is nothing more than a metering device for your refrigerant which adjusts the flow of freon into your coil to maintain a certain superheat. It cares about nothing except the superheat, which is there to protect your compressor, and to make your system a little more efficient in fluctuating conditions. If on the outside of your airhandler/coil, you see a large nut on the smaller copper line,or two nuts(compression fittings), you probably have a piston. Post model numbers and one of these Guru's can tell you....

[too tall terry]

A txv is nothing more than a metering device for your refrigerant which adjusts the flow of freon into your coil to maintain a certain superheat. It cares about nothing except the superheat, which is there to protect your compressor, and to make your system a little more efficient in fluctuating conditions. If on the outside of your airhandler/coil, you see a large nut on the smaller copper line,or two nuts(compression fittings), you probably have a piston. Post model numbers and one of these Guru's can tell you....i watched your boys go down Christmas Day..........TO is an a$$,and not a very good football player anymore...........hang in there brother...it will get better,this coming from a true Skins fan :D:D:D and yes,you should have a txv metered coil

[star882]

Thermal eXpansion Valve
It actually stands for *Thermostatic* eXpansion Valve. It's one of the most common types of expansion valves (other common types are capillary tube and CPEV) in use today. It can adapt to load changes, making it work better than capillary tubes for variable loads. The easiest way to see if it has a TXV is to look for a sensing bulb on the suction line. Or follow the liquid line to the evaporator coils and see if there's one installed. If all you see is a barrel (filter drier) and some thin tubes, it's capillary tube. If you see a strange looking valve with 3 or 4 pipes going to it (1 very thin (sensing bulb line), 2 fairly thick (coil and liquid line), 1 somewhat thin (equalizer if present)), it's a TXV. A CPEV will look like a TXV but without a sensing bulb or equalizer line.

[too tall terry]

It actually stands for *Thermostatic* eXpansion Valve. It's one of the most common types of expansion valves (other common types are capillary tube and CPEV) in use today. It can adapt to load changes, making it work better than capillary tubes for variable loads. The easiest way to see if it has a TXV is to look for a sensing bulb on the suction line. Or follow the liquid line to the evaporator coils and see if there's one installed. If all you see is a barrel (filter drier) and some thin tubes, it's capillary tube. If you see a strange looking valve with 3 or 4 pipes going to it (1 very thin (sensing bulb line), 2 fairly thick (coil and liquid line), 1 somewhat thin (equalizer if present)), it's a TXV. A CPEV will look like a TXV but without a sensing bulb or equalizer line.and just to add to this,the sensing bulb is filled with freon independent of the systems charge.....this is how the freon is throttled/metered through the txv itself :D

[coolguysfl]

It actually stands for *Thermostatic* eXpansion Valve. It's one of the most common types of expansion valves (other common types are capillary tube and CPEV) in use today. It can adapt to load changes, making it work better than capillary tubes for variable loads. The easiest way to see if it has a TXV is to look for a sensing bulb on the suction line. Or follow the liquid line to the evaporator coils and see if there's one installed. If all you see is a barrel (filter drier) and some thin tubes, it's capillary tube. If you see a strange looking valve with 3 or 4 pipes going to it (1 very thin (sensing bulb line), 2 fairly thick (coil and liquid line), 1 somewhat thin (equalizer if present)), it's a TXV. A CPEV will look like a TXV but without a sensing bulb or equalizer line.

Yes - my typo, too many things going on at one time.

[ramlam]

Thanks everyone for the great information. The model is a Lennox C23-51-1, an 11 seer, 4 ton A-coil. It's about 6 years old. Can anyone tell me if this model has TXV? Also, any thoughts on why the confort-r feature would require it? Here's the thread I found that mentions it needs it http://www.hvac-talk.com/vbb/showthr...ight=comfort-r

I will also try and post a picture of my coil.

[ramlam]

Here are some pic's from when they were installing my Trane furnace and had the A-coil exposed. Not sure if you can tell from these if it has TXV or not. 89

90

91

92

Thanks again for everyone's help

[Mr Bill]

Don't look to be a TEV, I sure don't like having a drier that close to the metering device, I have had a lot of pistons wash out because of folks putting the drier that close, maybe it don't make any difference but I have always had bad experiences with the driers that close.

[air2spare]

Don't look to be a TEV, I sure don't like having a drier that close to the metering device, I have had a lot of pistons wash out because of folks putting the drier that close, maybe it don't make any difference but I have always had bad experiences with the driers that close.


...but actually read directions on a drier box that said to install the drier close to the expansion device

[ramlam]

Well it has lasted 6 years without any issues, so hopefully I won't have any problems. Also, it doesn't look like I can do much about it now.

Thanks for the heads-up.

[Mr Bill]

...but actually read directions on a drier box that said to install the drier close to the expansion device


Yes but that's not an expansion device, probably a piston device. :D

[star882]

I don't see a sensing bulb or equalization line (unless they were somehow hidden in the picture), so it's either capillary tube or CPEV. Chances are, it's just a capillary tube.
If you could get a picture from the other side, I'll be able to tell for sure.

[ramlam]

The other side just has sheet metal over the coils and you can't really see anything other than sheet metal. Thanks anyway.

[star882]

Then show a picture above so I can see what, if anything, is hiding behind that piece of sheet metal.

[smokin68]

Highly doubt it's a cap tube. That appears to be a piston. The only time I could see the drier causing a problem would be if it was bad(restricted). Ours are installed like that, close to the MD.

[gsxrsquid]

piston

[ramlam]

Unfortunately the furnace is installed now and you can no longer see the a-coil, i.e. they put the ductwork around it and there is no access to it without removing the ductwork. I took the pictures when they installed it on Wednesday. Thanks anyway.

[t527ed]

it is a piston in there now. installing an expansion valve would be very easy to do. have your contractor price it for you.


lets see some after pics. expansion valve mounts on outside of that model coil so new plenum should not have to be opened.

[ramlam]

Thanks for the additional info. I feel more confident that the cost will be reasonable since they don't have to get into the sheet metal that surrounds the a-coil. I will post a picture when I get it done. Thanks again for the help.

[star882]

Thanks for the additional info. I feel more confident that the cost will be reasonable since they don't have to get into the sheet metal that surrounds the a-coil. I will post a picture when I get it done. Thanks again for the help.
Actually, they would have to cut off the capillary tubes and install a distributor, then braze it all together. But that shouldn't raise the price very much, if at all.

[gevans]

I don't think those are cap tubes, they are feeder tubes. No need to remove or replace. Piston device. Easy to replace from outside the coil box.
1. Remove piston
2. Tap gas line for sensing line
3. Install TXV
4. Clamp sensing bulb to gas line

[vette1992]

What is the difference between a TXV and a TXV-NB (non-bleed)? My system is using the TXV-NB coil.

Dwayne

[4l530]

It means the TXV won't allow the low and high sides equalize when the system shuts down.

[tact1999]

Which would be the ideal system choice? TXV or TXV-NB. In addition, is it true that by adding a TXV you may end up increasing the overall system SEER rating.

[panhead98]

worth about 1/2 SEER point - installed correctly.

[kevinmac]

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